1. Field of the Invention
The present invention relates to a method of producing an ink jet recording head that discharges ink to record, and an ink jet recording head produced by the method.
2. Related Background Art
An ink jet recording head generally includes a plurality of ink flow paths, each of which is communicated with each of a plurality of minute ink discharge ports, and an ink chamber commonly communicated with the plurality of ink flow paths. The plurality of ink flow paths and the common ink chamber are integrally referred to as an ink path. Energy generators, which generate energy which is utilized to discharge ink from the discharge port, are usually provided so as to correspond to the ink paths respectively. A typical example of the energy generators involves an electrothermal converting element which generates thermal energy as energy which is utilized to discharge ink, or a piezoelectric device.
As a method of producing such ink jet recording head, for example, Japanese Laid-Open patent Application Nos. 61-154947 and 62-253457 describe a method thereof comprising the steps of forming an ink path pattern on a substrate with a soluble resin, setting the pattern with an epoxy resin or the like to set the epoxy resin, and dissolution-removing the pattern of the soluble resin after cutting the substrate. This method is mainly described as a method of producing a type of ink jet recording head in which an ink discharge direction is substantially a vertical to a direction where ink is supplied onto an electrothermal converting element.
To obtain a high-definition recording image by an ink jet recording head, it is preferable that small droplets of ink, which are discharged from the discharge port are stably discharged at the same volume and discharge speed from the respective discharge ports. To realize such a stable ink discharge, each of Japanese Laid-Open patent Application Nos. 4-10940, 4-10941 and 4-10942 discloses a discharge method comprising the steps of applying drive signals to an electrothermal converting element in response to recording information, forming bubbles in ink by imparting thermal energy, which imparts rapid increase in temperature so as to exceed a nuclear boiling temperature of ink, to ink with the electrothermal converting element, and discharging ink as droplets by allowing the bubbles to communicate with the outside air. To realize such discharge method, it is preferable that the distance between the discharge port or orifice and the electrothermal converting element or heater is short as an ink jet recording head. The distance therebetween is hereinafter referred to as xe2x80x9cOH distancexe2x80x9d. In the above-mentioned discharge method, the OH distance substantially determines the discharge volume of the droplets of ink. Thus, it is important that the OH distance can be accurately and reproducibly formed.
Japanese Laid-Open patent Application No. 6-286149 discloses a method of producing an ink jet recording head which can shorten such OH distance and accurately produce it. A typical example of the production method described in this Application is carried out as follows in short. First, patterns of ink paths are formed on a substrate in lamination with soluble resin, a desired number of energy generators being arranged on the substrate. Then, by solvent-coating a mixture of a solvent and a coating resin melted in the solvent on the soluble resin layer, a coating resin layer, which will become the wall of an ink path, is formed on soluble resin layer. The coating resin contains solid epoxy resin at ordinary temperatures. Then, discharge ports are formed in the coating resin layer positioned on the energy generators, and ink paths are formed by dissolution-removing the soluble resin layer.
In the method of producing the ink jet recording head, ink droplets can be adhered to the periphery of the discharge port after the repetition of ink discharge or the like. The adhesion of the droplets can cause deviation between the discharge directions of droplets discharged from the discharge port by the degree of the adhesion thereof and cause troubles to high-definition and accurate recording. To prevent the adhesion of ink to the portion near the discharge port, which adhesion is the main reason of the deviation of the discharge direction, a method of carrying out a water repellent treatment of the discharge port region where the discharge port is formed is known.
The water repellent treatment for the ink jet recording head has been carried out by steps of transferring a water repellent applied to a flexible member of a silicone rubber or the like, to the discharge port region of the ink jet recording head produced by the above-mentioned method, and drying or setting the obtained structure. However, since, in the water repellent treatment, the water repellent treatment agent is also transferred to the opening region of the discharge port, it was difficult to prevent penetration of a small part of the water repellent into the discharge port. To obtain high quality level and high-definition recording images by the use of the ink jet recording head, each size of ink droplets discharged from the ink discharge port have been recently become very small. Therefore, the entrance of the water repellent into the discharge port, even if to the small extent, can effect on the discharge directions of the droplets.
One object of the present invention is to provide a method of producing an ink jet recording head which can discharge ink straight in aimed directions from a discharge port thereby to stably make high quality level and high-definition recording for a long term, and an ink jet recording head produced by the production method.
Another object of the present invention is to provide a method of producing an ink jet recording head in which a water-repellent material is not penetrated into the discharge port, and an ink jet recording head produced by the production method.
Still another object of the present invention is to provide a method of producing an ink jet recording head, which can correctly form a water repellent film having a thickness which has sufficient endurance to external causes such as paper jamming, paper rubbing with powder and the like, in a desired region, and an ink jet recording head produced by the production method.
Still another object of the present invention is to provide a method of producing an ink jet recording head, in which a discharge port surface provided with a discharge port, through which ink is discharged, is provided comprising:
a conductive treatment step of carrying out a conductive treatment of the discharge port surface in a state where a material is present in the portion of the discharge port;
a removing step of removing said material to open the discharge port; and
an electrolytic deposition step of electrolytically deposit a waiter repellent material in the conduction-treated region of the discharge port surface.
Still another object of the present invention is to provide a method of producing an ink jet recording head, in which a discharge port surface provided with a discharge port, through which ink is discharged, is provided comprising:
an unfinished-treatment step of treating the discharge port surface to the middle stage of a conductive treatment of the discharge port surface in a state where a material is present in the portion of the discharge port;
a removing step of removing said material to open the discharge port;
a treatment finishing step of finishing the conductive treatment; and
an electrolytic deposition step of electrolytically deposit a water repellent material in the conduction-treated region of the discharge port surface.
Still another object of the present invention is to provide an ink jet recording head produced by such methods of producing an ink jet recording head.
According to the present invention, prior to opening the discharge port a conductive treatment of the discharge port surface is carried out, or the conductive treatment is carried out in the middle stage. Consequently, when a water repellent coating material is coated with an electrolytic deposition process, only the discharge port surface other than the discharge port is water-repellent treated, whereby no water repellent coating materials is penetrated into the discharge port. Therefore, even if each size of ink droplets which are discharged is small, an ink jet recording head in which no deviation of the discharge direction occur can be produced. Further, according to the present invention, a water repellent film having a thickness which has sufficient endurance to the external causes, such as paper jamming, paper rubbing with powder and the like, can be correctly formed in a desired region.